#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_timer.h>

#include <stdio.h>
#include <math.h>
#include <errno.h>

#define SPEED 7
#define RADSPD 0.2
#define DELAY 40
#define MAPX 8
#define MAPY 8
#define PI 3.1415926535
#define DEG 0.01745329
#define HEIGHT 512
#define WIDTH 1232
#define TILESIZE 64
//#define SQRTTILE 6

struct player
{
	float x; 
	float y; 
	float dx; 
	float dy; 
	float th;
};

float dist(float x1, float y1, float x2, float y2)
{
	return ( sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)) );
}

int processEvents(SDL_Window *window, struct player *P, int map[])
{
	int done = 0;
	SDL_Event event;
	while(SDL_PollEvent(&event))
	{
		switch(event.type)
		{	
			case SDL_WINDOWEVENT_CLOSE:
			{
				if(window)
				{
					SDL_DestroyWindow(window);
					window = NULL;
					done = 1;
				}
			}
			break;
			
			case SDL_KEYDOWN:
			{
				switch(event.key.keysym.sym)
				{
					case SDLK_ESCAPE:
						done = 1;
						break;
				}
			}
			break;
			
			case SDL_QUIT:
				done = 1;
			break;
		}
	}

	const Uint8 *state = SDL_GetKeyboardState(NULL);
	if(state[SDL_SCANCODE_A])
		P->th -= RADSPD;

	int xoff = 0;
	if((P->dx)>0) {xoff = 20;} else {xoff = -20;}

	int yoff = 0;
	if((P->dy)>0) {yoff = 20;} else {yoff = -20;}

	int px64 = (int)(P->x) >> 6;
	int py64 = (int)(P->y) >> 6;

	int pxadd = (int)(P->x + xoff) >> 6, pyadd = (int)(P->y + yoff) >> 6;
	int pxsub = (int)(P->x - xoff) >> 6, pysub = (int)(P->y - yoff) >> 6;

	if(state[SDL_SCANCODE_W]) {
		if(map[py64*MAPX + pxadd]==0) {P->x += P->dx;}
		if(map[pyadd*MAPX + px64]==0) {P->y += P->dy;}
	}
	if(state[SDL_SCANCODE_S]) {
		if(map[py64*MAPX + pxsub]==0) {P->x -= P->dx;}
		if(map[pysub*MAPX + px64]==0) {P->y -= P->dy;}
	}
	if(state[SDL_SCANCODE_D])
		P->th += RADSPD; 

	if(P->th < 0)
		P->th = 2*PI - 0.00001;
	if(P->th > 2*PI)
		P->th = 0.0;

	P->dx = cos(P->th)*SPEED;
	P->dy = sin(P->th)*SPEED;

	return done;
}

void drawLevel(SDL_Renderer *renderer, int map[], struct player P)
{
	for(int y = 0; y<MAPY; y++)
		for(int x = 0; x<MAPX; x++)
		{
			if(map[y*MAPX + x])
			{
				SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
			} else {
				SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
			}

				SDL_Rect wall = {x*TILESIZE, y*TILESIZE, TILESIZE-2, TILESIZE-2};
				SDL_RenderFillRect(renderer, &wall);
		}		
}

void drawPlayer(SDL_Renderer *renderer, struct player P)
{
		SDL_SetRenderDrawColor(renderer, 255, 220, 0, 255);
		SDL_Rect rect = {P.x-5, P.y-5, 10, 10};
		SDL_RenderFillRect(renderer, &rect);

		SDL_Vertex arrow[3];
		arrow[0].position.x = P.x+5*cos(P.th-PI/2);
		arrow[0].position.y = P.y+5*sin(P.th-PI/2);
		arrow[0].color.r = 255;
		arrow[0].color.g = 220;
		arrow[0].color.b = 0;
		arrow[0].color.a = 255;

		arrow[1].position.x = P.x+5*cos(P.th+PI/2);
		arrow[1].position.y = P.y+5*sin(P.th+PI/2);
		arrow[1].color.r = 255;
		arrow[1].color.g = 220;
		arrow[1].color.b = 0;
		arrow[1].color.a = 255;

		arrow[2].position.x = P.x+20*cos(P.th);
		arrow[2].position.y = P.y+20*sin(P.th);
		arrow[2].color.r = 255;
		arrow[2].color.g = 220;
		arrow[2].color.b = 0;
		arrow[2].color.a = 255;

		SDL_RenderGeometry(renderer, NULL, arrow, 3, NULL, 0);
}

void drawRays(SDL_Renderer *renderer, struct player P, int map[])
{
	int mx, my, mp, dof;
	float rx, ry, ra, xo, yo, px, py, hlen, vlen, sinra, hx, hy, vx, vy, rdist;
	ra=P.th-45*DEG;
	if(ra<0)
		ra += 2*PI;
	if(ra>2*PI)
		ra -= 2*PI;

	px = P.x;
	py = P.y;
	float antan;
	for(int r = 0; r<90; r++)
	{
		// ----- по горизонтальным -----
		hlen = 100000;
		dof = 0;
		sinra = sin(ra);
		if(sinra<-0.001)	// "вверх"
		{
			antan=-1.0/tan(ra);
			ry = (((int)py>>6)<<6)-0.0001;
			rx = (py-ry)*antan+px;
			yo = -64;
			xo = -yo*antan;
		} else {
		if(sinra>0.001)
		{
			antan=-1.0/tan(ra);
			ry = (((int)py>>6)<<6)+64;
			rx = (py-ry)*antan+px;
			yo = 64;
			xo = -yo*antan;
		}
		else
		{
			rx = px;
			ry = py;
			dof = 8;
		}}

		while(dof<8)
		{	
			mx = (int)(rx)>>6;
			my = (int)(ry)>>6;
			mp = my*MAPX+mx;

			if(mp > 0 && mp < MAPX*MAPY && map[mp]==1){
				hx = rx;
				hy = ry;
				hlen = dist(px, py, hx, hy);
				dof = 8;
			} else {
				rx += xo;
				ry += yo;
				dof++;
			}
		}
		//SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
		//SDL_RenderDrawLineF(renderer, P.x, P.y, rx, ry);
		// ----------

		// ----- по вертикальным -----
		dof = 0;
		vlen = 100000;
		float cosra = cos(ra);
		if(cosra<-0.001)	// "влево"
		{
			antan=-tan(ra);
			rx = (((int)px>>6)<<6)-0.0001;
			ry = (px-rx)*antan+py;
			xo = -64;
			yo = -xo*antan;
		} else {
		if(cosra>0.001)
		{
			antan=-tan(ra);
			rx = (((int)px>>6)<<6)+64;
			ry = (px-rx)*antan+py;
			xo = 64;
			yo = -xo*antan;
		}
		else
		{
			rx = px;
			ry = py;
			dof = 8;
		}}

		while(dof<8)
		{	
			mx = (int)(rx)>>6;
			my = (int)(ry)>>6;
			mp = my*MAPX+mx;

			if(mp > 0 && mp < MAPX*MAPY && map[mp]==1){
				vx = rx;
				vy = ry;
				vlen = dist(px, py, vx, vy);
				dof = 8;
			} else {
				rx += xo;
				ry += yo;
				dof++;
			}
		}

		if(vlen < hlen) 
		{ 
			rx = vx; ry = vy; rdist = vlen; 
			SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
		}
		else { rx = hx; ry = hy; rdist = hlen; 
			SDL_SetRenderDrawColor(renderer, 200, 0, 0, 255);
		}
				
		SDL_RenderDrawLineF(renderer, P.x, P.y, rx, ry);

		// ----- Рисуем стены -----
		float corran = P.th - ra;
		if(corran<0)
			corran += 2*PI;
		if(corran>2*PI)
			corran -= 2*PI;
		rdist *= cos(corran); // рыбий глаз
		//rdist += 20;

		float lineh = (64*HEIGHT)/rdist;
		if(lineh>HEIGHT)
			lineh=HEIGHT;
		float lineo = HEIGHT/2 - lineh/2;

		SDL_Rect line = {64*MAPX+r*8, lineo, 8, lineh};
		SDL_RenderFillRect(renderer, &line);

		ra += DEG;
		if(ra<0)
			ra += 2*PI;
		if(ra>2*PI)
			ra -= 2*PI;
	}
}

void Render(SDL_Renderer *renderer, int map[], struct player P)
{
	SDL_SetRenderDrawColor(renderer, 128, 128, 128, 255); // фон
	SDL_RenderClear(renderer);
	SDL_SetRenderDrawColor(renderer, 90, 90, 100, 255); // пол
	SDL_Rect floor = {0, HEIGHT/2, WIDTH, HEIGHT/2};
	SDL_RenderFillRect(renderer, &floor);
	drawLevel(renderer, map, P);
	drawRays(renderer, P, map);
	drawPlayer(renderer, P);
	SDL_RenderPresent(renderer);
	SDL_Delay(DELAY);
}

int main(void)
{
	SDL_Window *window;
	SDL_Renderer *renderer;
	
	SDL_Init(SDL_INIT_VIDEO);

	window = SDL_CreateWindow("Raycast",
				  SDL_WINDOWPOS_UNDEFINED,
				  SDL_WINDOWPOS_UNDEFINED,
				  WIDTH,
				  HEIGHT,
				  0);

	renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
	struct player P = {100, 100, 0, 0, PI/2};
	// int mapT = 64;
	int layout[MAPX*MAPY] = 
	{
 	1,1,1,1,1,1,1,1,
 	1,0,1,0,0,0,0,1,
 	1,0,1,0,0,0,0,1,
 	1,0,1,0,0,0,0,1,
 	1,0,0,0,0,0,0,1,
 	1,0,0,0,0,1,0,1,
 	1,0,0,0,0,0,0,1,
 	1,1,1,1,1,1,1,1
	};

	int done = 0;	// bool завершения программы

	while(!done)
	{
	// проверка событий
		if(processEvents(window, &P, layout) == 1)
			done = 1;
	//rendering 
		Render(renderer, layout, P);
	}

	SDL_DestroyWindow(window);
	SDL_DestroyRenderer(renderer);

	SDL_Quit();
	printf("!%d!", errno);
	return 0;
}